Endoscopic transphenoidal pituitary tumor removal involves removing the floor of the sella turcica, opening the dura mater, and then removing the tumor with a variety of microsurgical techniques. These tumors can extend beyond the sella turcica and intwine with the meninges. Surgical removal of a tumor may disrupt the meninges, leading to the leakage of spinal fluid into the surgical field. Because the spinal fluid is under pressure, the fluid may continue to leak and maintain a communication between the intracranial space and the nasal/sinus space which may lead to conditions such as pneumocephalus, encephalitis, and meningitis.
During transphenoidal surgeries such as endoscopic transphenoidal pituitary tumor removal, a surgeon typically re-creates the barrier between the sphenoid sinus and sella turcica to prevent the spinal fluid leak and communication between the intracranial space and the nasal/sinus space. The surgeon generally uses an inlay, an overlay, or a combination of the two to re-create the barrier.
Inlay materials are placed on the brain side of the sella turcica. Inlay materials serve as structural support to counter the ongoing downward forces of the spinal fluid and meninges resulting from spinal fluid pressure and gravity. Inlay materials include bone, cartilage, and other less structurally sound materials such as fascia, pericardium, or dura harvested from the patient, or provided from a tissue bank. Bone and cartilage may provide significant support to prevent the slow, persistent herniation of meninges in the days and weeks after surgery leading to cerebrospinal fluid leaks. However, bone is difficult to work with due to sharp edges that may need to be removed, and due to the small custom shape needed to be created. The bone needs to be sized larger than the hole, making it difficult to place through the craniotomy. Patient cartilage is often too weak, and cracks when handling. While cadaveric rib cartilage is nearly ideal, it is a bit too rigid and time consuming to customize. Cadaveric rib cartilage is also not readily available, and is expensive.
Overlay materials do not provide long lasting structural support. Some overlays “plug” the hole using fat grafts, cellulose packing materials, or injectable glues. Other overlays cover the hole with fascia, dura, or mucosal grafts. Overlay materials such as mucosa, fat, gel foam, surgical glue, collagen, etc are easy to place and readily available. Fat requires a separate abdominal incision. These materials provide no structural support and rely on the hope that tissue ingrowth and healing will occur before the herniation of meninges and cerebrospinal fluid overcome them. Overlays are often sufficient for small meningeal penetrations; however, for medium to larger cerebrospinal fluid leaks, overlays are generally insufficient.
Overlays often lead to delayed cerebrospinal fluid leaks. The tissue used in the overlays often resorbs or mobilizes out of position with development of a cerebrospinal fluid leak.
U.S. patent application No. 2007/0270841 to B. Badle discloses implantable devices that may be positioned, for example, into the sphenoid sinus or sella turcica of a subject. In certain embodiments, the implantable devices comprise a center plate and a plurality of protruding arms extending from the center plate, both of which may be composed of bioresorbable material. In particular embodiments, the implantable devices are configured to help reconstruct the sellar floor after it has been damaged in order to prevent cerebrospinal fluid leaks.